Fabrics as they come from the loom or the knitting machine in their unfinished state are referred to as greige or grey goods. They may contain warp sizing, trash, oils and off-color impurifications called motes. Before they are ready for the customer the fabrics are desized, scoured, bleached, dyed and finished. Approximately eighty per cent of all cotton fabrics are bleached with hydrogen peroxide.
Hydrogen peroxide bleaching solutions are normally quite unstable as they are decomposed by the action of sunlight, metallic impurities and organic matter. To prevent excessive decomposition of hydrogen peroxide it is stored and shipped in glass, aluminum or stainless steel. In the bleaching process for textile fabrics using hydrogen peroxide as the bleaching agent, an alkali such as sodium hydroxide or soda ash is often used along with a stabilizer which throughout the years has been silicate of soda sold as water glass.
The use of water glass as a stabilizer for hydrogen peroxide solutions has presented objectionable processing problems which have been endured by the textile industry. Water glass creates a serious scaling problem on the bleaching equipment which interferes with the flow of the fabric through the bleaching process. Where hard water is encountered the scaling often clogs feed tanks and pipe lines which requires that the equipment be shut down for cleaning. Splashes and spills on the floor leave a heavy white crust which is difficult to remove and creates a walking hazard to the employees.
The water glass is also objectionable with respect to the cloth being bleached. When silicate solids deposit on the goods, a harsh handle or feel results and the absorbency of the goods will be substantially lower in those places where deposits have occurred. This causes serious difficulties in dyeing operations as uneven dyeing takes place.